You installed Acronis Cyber Protect Home Office and signed in.
After clicking Enter serial number, you submit a short subscription key (16 symbols).
After you press Activate, the activity indicator runs for some time, then Activate and Cancel buttons reappear. No error message is shown.
Issue in the product: user interface glitches when a short subscription key is provided.
This issue will be fixed in the next update.
When the activity indicator (3 moving dots) stops and Activate button reappears, close Acronis Cyber Protect Home Office, then run it again: activation should be applied correctly after this.
Alternatively, register the short subscription key under your Acronis Account on the website: see Registering Acronis products at the website, then re-launch Acronis Cyber Protect Home Office. If you are signed in, the software will automatically get the subscription information from the account.