I'm not able to search for specific files in a folder saved on SD card on Macbook air
You should try the cool, (and free,) app EasyFind by developer Devon Technologies. It searches for files where Finder can't search well, or can't search at all. I use it at work for searching for files in very complex macOS folder structures shared on Windows servers, and it is fast.
Alternate download site.
Disclaimer: I'm a very satisfied user of EasyFind and other Devon Technologies apps, and have no financial or other involvement in the company.