Just put the Blend file in your Assets library folder and you are good to go.

In the Asset Library there are two types of Assets 'Collection' & 'Object'

for Collection assets you need to uncheck  instance option to use them 

◆ In Blender 5.0 for using collection Assets :

In Preferences -> File Paths   just set the Import method to Append and then save preferences :

You can set this in Asset manager as well :

                                                                                                                                                ENJOY :D!