Unfortunately, maps were removed after the V21 update. If you wish to view maps again you'd have to downgrade to V20.
You can download V20
here, after the download is complete all you have to do is open the installer and follow the instructions to install it. Keep in mind it is probably a good idea to install it in a location different than in My Documents as it will cause your current Blockland to be overwritten.
After the install is complete do not open Blockland like you normally would! It will cause it to be updated to V21 again, which you do not want. Open the folder that you installed V20 in, and open "launcher.bat", this will open V20 and allow you to play it.
Remember, you cannot join servers with V20, so you have to play single player. Have fun and enjoy!
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