It might be that your data partition does not have enough space for downloading.
there are 3 options: free space on data partition, try rupors root package with apps2sd fix or repartition everything. the latter one is very dangerous. you will find infos on that in the wiki and in the developers subforum.
just to be sure you know: google market won't work out of the box, you have to install 2 more apks before that. there are complete packages will all 3 apks linked in the wiki:
https://wiki.mobileread.com/wiki/PRST...rket_Procedure
I went with the froyo version.