300 * 265 = 76800. The largest texture size Unity supports is 4096*4096 with mobile being 2048*2048. You'll need to split them up into many atlases.
Also you are wasting a LOT of texture space. The striped background could take up 32*32 total and be turned into a tiled sprite, Eureka could be text or just a single sprite on the sheet. With that many sprites you should really be trying your best to save texture (and thus memory) space.