Hi @Aaron_Bm and welcome to PlayCanvas. Unfortunately, you cannot do mesh-to-mesh collisions in PlayCanvas due to the limitation of it’s physics engine, Ammo.js. The simplest method of moving a capsule independently of the entity itself is to add the model as the parent entity, and the rigidbody as a child entity, thereby allowing you to move them independently. However, sharing your project link may help in this, as the building model’s mesh also could have a few issues, thus leading to your issue.
P.S - If you find PhysX more suited to your needs instead of Ammo.js due to your experience in Unity, @LeXXik has built an awesome project integrating PhysX into PlayCanvas - PlayCanvas with NVIDIA PhysX
Hope this helps!