The motherboard does not have a GPU, the iGPU is on the CPU, if you have a CPU with an iGPU. For AMD, these are only the CPUs with a G (AMD Ryzen) at the end of the name or the Athlon or A-Series APU.
E.g.: Ryzen 5 3400G

If you do not have a G at the end, you cannot use the outputs of the mainboard.

For such problems, it can be worthwhile to have a 50.- emergency graphics card at home, a recommendation from my side.