Hi @STW ,
You can explore all PowerApps capabilities for free by signing up for a PowerApps Plan 2 license that expires after 30 days. To use PowerApps later, you need to purchase either Plan1/2 or you need to have Office 365 or Dynamics 365 account. See in PowerApps pricing page here:
https://powerapps.microsoft.com/en-us/pricing/
Regards,
Mona