Mediatek mt7628an

I'm new to LEDE and want to build it for the RAK WisAP which has an Mediatek mt7628an core. I've builded the source code with selecting "MediaTek Ralink MIPS" and "MT76x8 based boards". In the target directory I've got several bin files for specific boards, I also find one that looks more general to me "openwrt-ramips-mt76x8-u7628-01-128M-16M-squashfs-sysupgrade.bin". I've flashed it into my board but during startup it hangs without any error.

I've tried to match the working older openwrt version supported by the manufacturer with the LEDE source and there I found this file:

I see this similar file in the LEDE source

Is this file something that I need to get it working? Or is there something else to get the correct target bin file? Or do I use the correct file but is it not working for this board yet?