gpu memory, not ram mb
I see. So your PC lacks a discrete GPU at all. Instead, it relies solely on that integrated AMD graphics that's on the CPU itself. Well, that integrated GPU is only good for giving you a display on your monitor, and it is much too feeble for anything which calls for GPU acceleration.
In addition, the reason why Filmora worked well for you is that Filmora offers very little, if any, GPU-accelerated features. Almost everything that's done in Filmora is CPU-only (or software-only). Premiere Pro, on the other hand, is much more GPU-intensive than Filmora will ever be. In other words, that puny integrated AMD Radeon Graphics got severely overworked when working in Premiere Pro.
As a result, you really need a discrete (meaning internal expansion card) graphics card in order for Premiere Pro to run at its best. And do not go for an old or low-end graphics card because it will not be much better than just your integrated CPU-based graphics to justify its current street price.