[Adding Affinity to second personal computer]

I purchased a license of Affinity Photo through the Apple store.  I have an iMac and MacBook.  When disks were available, I would upload to each computer and use the serial number to activate.  In the information that I read about Affinity, it indicated that the license covered a second personal computer.  I have no idea how to proceed.  I too think that a manual would be very helpful and appreciate that it coming.  Thank you the videos on how to use Affinity, but I have not found any practical advice on how to set up the second computer.   Thank you for your consideration.  I am enjoying Affinity.