Anker solar panel is not designed to your use case.
The sun moves so solar panel needs to moves with it, and solar energy is significantly depleted indoors. They are designed to fold out pointing sun-ward when living off-grid.
Rigid solar panels work better for permanent installations.
I have a had a love/hate 20 year relationship with solar, currently I still prefer to pack a bigger battery instead, on average it works best. I did a test off-grid for 4 days in July and solar worked ok as was sunny all the time, then did a 3 week off-grid in September and rained a lot and didn't work so well. My ideal solution would be a 2 port 15Ah Powercore which recharged fully in 2-4 hours, that amount of energy would last me 3-4 days and I'd recharge indoors like over a pub lunch and most backpackers pass electricity every few days.