To add to what Claudio said you can do all what you want, natively inside WB Mechanical, using combin14 for spring and mass21 for mass.
1. You need a freestanding remotepoint at the mass location.
2. Define a point mass using remote points on the above defined point/location (this will be the mass21 element)
3. Finally define a spring connection using the remote point for the mobile (spring def.) the remote point and a node or if you have a vertex on your beam element for the reference side (spring def.). This is the combin14.
So we should have in our Mechanical tree, 1 remote point (free standing), 1 point mass (under the geometry tree), and one spring (under connections).
All the best