Problems digitising cassette tapes

Hi there,
I’m desperate for someone to help me to figure out what I’m doing wrong. I’m attempting to convert some old cassette tapes of my mum singing to digital for my family using Audacity.
I’ve looked at a bunch of YouTube videos on the subject but I seem to be doing something wrong.
I’m not sure if it’s an incorrect setting or two in Audacity which is causing the problem, but I can’t seem to get it to work. I’m using a Grundig cassette player with left and right “Line out” going to a laptop running Windows 10 which has 1 combined jack socket. (headphones and mike)
Audacity seems to be able to pick up my voice from my laptop’s on-board microphone, but when I try to play the tapes through a cassette recorder connected via RCA cables into the computer via a combined jack socket, it still just picks up the microphone. The signal is not going through the cable into the laptop.
Just for your information, I have sent some additional photos to show the equipment I’m using, and how it is all plugged together. I absolutely don’t know what’s going on, please help regards, Gin.
PS. I managed to make this work about six months ago, although then, the laptop I was using was running Windows 7 and I was using a different cassette player. (It’s not possible to use this things again as I don’t have them anymore)
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