PHP requirement to chose the right hosting

I successfully installed my premium theme but for importing the main demo, I always get an error that says “Demo import failed. Please check for PHP limits and change those to the recommended value and try again.” Now I ould like to know the requirement for this theme. I’m with siteground shared webhosting and I’m using wordpress. One more, I don’t have a import button on the highend options so I have to do it manually.