Hi!
First you have to get your weak account key. In your BOINC profile click in the account key link, or use this link, copy the weak account key. Next, at http://foldforcovid.local click the button Change Account Key and paste the weak key, press Apply and your system will restart. Now your old laptop is using the same account as your desktop.
Warning: When I did this the tasks that my old computer were aborted. If you like to avoid this follow the instructions in this post to complete the tasks in your old laptop.
If you have any questions, please ask.