Convert SimCity 4 retail copy to digital

I'm trying to install the now ancient SimCity4 using a physical copy I have lying around. However, the setup gets stuck at 44.80% and doesn't tell me to insert the 2nd disc. I did so anyhow, yet still it did not progress beyond that percentage.

I've seen that it is/used to be possible to convert your retail copies to digital ones within Origin. Since we've now got the EA app, I'm wondering if and how I can do this.

Tried getting in touch with support, but of course I cannot select this product as since it's so old. Tried selecting SimCity Buildit instead, and still couldn't fill out the form as I literally can't select anything in the console field.

Help or suggestions would be much appreciated.