REDCap is accessible from any kind of device with a secure internet connection. REDCap has good security because sensitive data never leaves the secure data center which contains its secure servers. You can import data into REDCap as well as export data from REDCap.
REDCap databases are backed up on a regular schedule; the data backups are kept in a safe environment and are recoverable.
There is enough space for most research projects; larger research projects are handled on a case to case basis. In general, there is no limit to the number of studies that you can have.