Both should work, even with a non-AVM router. However, the repeater will always work as a repeater, i.e. it will 'extend' the original network. As far as I know, it cannot be operated as a pure receiver, the repeater function cannot be switched off.
From the manual (
https://assets.avm.de/files...):
Requirements
- Router with automatic IP address assignment (DHCP)
- For operation as a WLAN repeater: FRITZ!Box or other WLAN router according to IEEE 802.11ax, IEEE 802.11ac or 802.11n
And for the LAN socket: Gigabit Ethernet connection for:
- Connection of PC, notebook, games console, Smart TV and other network-compatible devices