The port may not run well on older PSP-1000 hardware due to RAM limitations, though it generally performs better on modern Android devices via PPSSPP.
Create a folder named SonicMania at the of your internal storage (or memory stick) and place the Data.rsdk file there. sonic mania ppsspp isoroms android download link
If you find the PPSSPP setup too complex, there are native Android options: Sonic Mania on the PSP?! Well... sort of The port may not run well on older