Convert ALTIUM file to Autodesk EAGLE: what is the most recent procedure?
Importing the Gerber files, as @Voltage Spike suggested works nicely in Autodesk EAGLE version 9.x.x:
Can you load Gerber files back into a PCB layout designer such as Eagle?
You just need to be aware of the layer assignments, which are provided by Altium:
https://www.nexpcb.com/blog/what-is-a-gerber-file-and-how-to-i-get-one