Shape Software programs for the Mac are 32-bit, and there are no plans to upgrade to 64-bit, as this would require massive rewriting. With the upgrade from Mojave to Catalina (OS 10.15) 32-bit programs are no longer supported. If you have not upgraded to Catalina yet, it may be best to find out whether you have many other 32-bit programs. If so, it may be better to install Catalina to an external disk or new volume rather than upgrading immediately. Be sure to back up your current system with Time Machine or other software before doing anything to the disk on which it is located (including upgrading to Catalina).
To keep running the Shape Software programs (and other 32-bit programs) Mac users have three basic options, other than just staying with Mojave or other older system.
A. You may be eligible for a free or low-cost switch to a Windows version. Email to support@shapesoftware.com
B. Run two Mac OS's with commercial software. Parallels Desktop and VMware Fusion are the leading options, although there are others. These are claimed to be able to run multiple operating systems, including Windows, without having to rebooot. You can install an older Mac system which will run 32-bit programs, or install Catalina separately without updating your current OS. See option C for how to get installation files for different Mac systems. Follow the instructions for the commercial software.
C. Multiple boot of OS's. A second operating system may be installed on a separate volume, which may be on an external disk (USB3 or thunderbolt) or the main hard disk, and you can choose which to boot on startup or restart. If the disk is formatted as APFS, a new volume may be defined without repartitioning. Depending on what your pre-Catalina system is or was and whether you have already upgraded to Catalina the options may be somewhat complex.
It may be best to make sure you can get the complete installation file for Mojave or other older system first. Here are links (as of 10/9/2019) to download the files for Mojave and Catalina:
Get complete Mojave installation file from Apple Store.
Get complete Catalina installation file from Apple Store.
These will link to the Apple Store. Click on GET to download. When the download is complete and the installation itself starts, click on Quit in the File menu if you have not already set up a disk volume on which to install as described below (do not install to your current system volume). The installation app (Install macOS Mojave.app or Install macOS Catalina.app) will be in your Applications folder. This article gives information about how to get other earlier OS's. It also describes how to make an installation flash or other USB drive, but this is not necessary to install on a volume other than your current operating system volume - you can just use the downloaded app.
Apple frequently changes the way that installation packages for old systems are accessible, so it may be necessary to do some searching on the internet if the above links do not work.
You must identify or set up a suitable volume, other than the one containing your current OS, using the Disk Utility Program (Applications/Utilities) It should not be necessary to use an entire external hard disk. A volume or partition for Mojave may not need much space, probably not more than 20G, unless you have 32-bit apps which require a lot of space themselves. If you are already using an external disk for Time Machine, you can make a new volume on that disk for the older operating system. If you want to use your main internal hard drive and it is APFS formatted, you can probably just define a new volume if there is sufficient unused space. Volumes defined in this way do not have to have a fixed size. If the drive is formatted in another way, a new fixed-size partition will have to be made, or an existing one used.
Now you can double click on the Install macOS Mojave.app you downloaded as above. When prompted for the volume on which to install, select the one you have set up - NOT the current operating system volume. If you want to try Catalina without upgrading and replacing your current OS, which may be the best option if you have many 32-bit programs, you can use the same procedure to install it.
Once the new OS is installed, to switch between operating systems it is necessary to shut down or restart and hold down the Option key as the chime sounds until you see the possible boot volumes. Or, before shutting down in one system, go to Startup Disk in System Preferences, unlock and choose the appropriate volume for default startup.
Shape Software programs on the internal system drive running Catalina (upgraded from previous Mojave or other system) can be run from the Mojave OS on another volume, so it should not be necessary to duplicate all 32-bit apps and data on both systems, although some apps will require installation of additional resources in a fresh installation of Mojave.