Hey Martin,
the use of Phoenix M17 connectors is relatively new on the Mechatron spindles, many datasheets still show the older connector. The Phoenix M17 is more reliable regarding vibrations, but also more expensive.
Most spindles have what you mentioned “aviation connector”, so either you find the plug for it for a larger cable, or if you want to switch to the Phoenix M17, you’ll probably have to exchange the connector on the spindle too, the connector at the cable side mentioned above would match this (or this) for device side.
But the easiest thing would be to find the connector matching the one on your spindle. Which one did you buy? Do you have a photo of the spindle connector?