As most people know, Apple have dropped support for 32-bit apps in Catalina.
We’re working on a 64-bit version of Freeway. Unfortunately, Apple have abandoned many of the (32-bit) APIs that Freeway uses (rather than providing 64-bit versions) so we’re rewriting Freeway from scratch. This is a major undertaking, but we’re making good progress.
We hope to release a public beta version later this year, but it’s going to take a while before the new version of Freeway is a complete replacement for Freeway 7 - so there could be a transitional period in which you may want to keep Mojave on a separate partition for when you need to run Freeway 7 (or other 32-bit software).
Another option is to run Mojave in a virtual machine (VM) such as Parallels or VMware.
There is a TidBITS article which explains how to do this:
IMPORTANT: Apple tend to remove installers for previous versions of macOS whenever a new version is released, so it’s a good idea to download the Mojave installer now, before it disappears. The TidBITS article explains how to do this.