We have found a bug on MacOS 10.15 where the users are unable to select .dat file (license file) to activate their license through the license wizard.
The workaround is as follows:
Quit Evolve/LicenseWizard
Copy the license file to /Applications/Evolve 2017.3.4/Security
Rename the copied file as altair_lic.dat
Launch Evolve
If the problem persists or you are unable to activate your copy of the license, send us a support request here