Don't Install if You Don't Have a Spare Mac or a Plan
You shouldn't install the macOS Catalina beta on your only Mac if you need it to get work done. If that is your only option, you should at the very least make a separate partition or install on an external hard drive.
There is a very good chance that you will see issues with this beta and that things you need to work every day may stop working correctly.
If you can't install on a second Mac or at least on a partition so that you can easily get back to macOS Mojave when you need a more stable experience do not install the beta.
Yes, you can downgrade, but it's a process and you don't want to be dealing with it in the middle of major project.
You can use our macOS 10.15 beta installation guide to learn about your options and how to install on a second partition.