i could be going at this the laziest possible way, im having a hard time understanding the groups and just all of it, and im just trying to add a bunch of new crate spawns to each of the monuments, however i can't seem to get it to respawn once looted once, not to mention barrels/door barricades are unable to be destroyed, anyone got any tips etc? 

Entities spawned via maspawn will be indestructible and will not respawn (if despawned for any reason such as due to looting them).

Barricades, loot crates, and barrels are spawned in vanilla via spawn groups. If you want to mimic vanilla behavior, you'll have to use the spawn groups feature of the plugin. Basically a spawn group is just a collection of spawn points, so that multiple spawn points can share information, which solves several use cases that are not otherwise possible.

When you use the maspawngroup create command (see documentation for exact usage), it's basically just creating a spawn point. If you don't have a use case for multiple spawn points sharing information, then you can just create each spawn point via the maspawngroup create command which will create an independent spawn point. If you do have a use case for multiple spawn points sharing information, then you'll want to use the maspawnpoint create command (see documentation for exact usage) to add more spawn points to an spawn group that you created via maspawngroup create.

I strongly suggest going through the commands in the "Creating spawn points" section of the documentation. Create the points, and look at the debug information in game. That should help you understand. If you are just looking at the docs without trying it in-game, then you will probably have a hard time connecting the dots. Also, trying using the mashowvanilla command at a monument to see how the vanilla spawn groups/points work.