If you have purchased GameMaker Studio 2 from the Steam platform, you can now attach your Steam account to the YoYo Account system. In order to do this you first have to register for a YoYo Account (YYA), here:
When you register, you will be required to fill out some personal details and then submit them to YoYo Games. After submission you will receive a confirmation email with a link to activate the YYA. The link will activate your account and permit you to log in on the YYA pages, where you can then link your Steam user details to the YYA. This is done from the Settings - Linked Accounts tab, by clicking the highlighted button shown below:
Clicking this link will open a new window where you will be requested to sign into Steam and confirm that the account is to be linked to YoYo Games. Once you have confirmed that it can be linked, you should see the following message confirming that your Steam account is now linked:
Please note your Steam profile has to be public in order for the Steam Account to be found. (Remember to disable any web extensions that block certain pages)
Now that you have linked your Steam install to your YoYo Account, you will see your purchased licences appear on your Products page and be able to download your stand-alone copy of GameMaker Studio 2 from your Downloads page.
After installing and starting the program, you will be presented with a login screen, you will need to enter your YoYo Account information and press the Log In button.
If all has gone correctly, you will now be able to use the GameMaker Studio 2 products you have purchased on Steam through the standalone version of the software.