In that case, it would seem to be an issue with running the installation of the drivers — is your Surface fully patched/up-to-date? (I’m hanging back at 1703 on my stylus machine, a Samsung Galaxy Book 12 'cause I can’t stand how MS crippled styluses in Fall Creators Update).
Have you tried:
- making a new admin account
- cold reboot
- installing the app in the new admin account
?