@ Carolin
re: Oddly, my client’s host only provides 48M of memory.
Really!?! How odd and surprising. Which host, if I may ask?
48MB will not give you much wiggle room I suggest temporarily installing the Query Monitor plugin to see how close to that limit you’re getting. It’ll add a nifty admin bar item, just clicking on it (not any of its submenu items) will take you to a section which will show you the “Peak memory usage”.
re: I was able to install & activate both Jupiter and Connections without any issue. They have now decreased it back to 48M but the error message has not come back! So fingers crossed it stays that way. If not, I’ll move the site to a different host.
If you have to move, I suggest SiteGround at least the GrowBig WordPress hosting plan. The price is very good with excellent performance and support. (I do not get anything for this recommendation, just a very satisfied customer who was disappointed with several other very popular hosts).
Hope that helps!