These are the sub-assets. You subscribed to some buildings or other assets that have these smaller ones integrated in them, but the asset creator didn't mention them as a requirement.

Use Loading Screen Mod(LSM) and enable logging. Check where the LSM is storing the logs, load the game, exit and go to the folder where the logs are. You will have the list of missing ones(among other things). Use that list to add the missing assets.

This is no issue of the Map, it does not use these assets. You are missing them from other Assets you are subscribed to. Go to the Reports Folder of the LSM Mod and open the latest Report file. The missing assets are listet there with a link to the Workshop so you can download them.