Solved! What kind of ram should I buy to upgrade this laptop

Memory installed: 8192 MB, DDR4-2666, 19-19-19-43

DDR4-2400 or DDR4-2666 Memory Type

2 SODIMM Slots available, one Dimm already installed

Max. Capacity 32GB

For best compatibility use a tool like CPU-Z and click on the SPD tab. There the already installed memory should be shown with its specifications and manufacturer including the model number, like: