Creating first snapshot manually

Hello,

I'm trying out Snapshot Pro plugin and I'm unable to create first snapshot manually - no matter if I choose save locally or upload to dropbox. Process runs for a while - I can see on FTP that it's creating a big ZIP file which usually takes up to 250 MB, but then it all stops (apparently). No information in plugin's panel about the progress, I can see two files on FTP - snapshot-backup.zip (262 MB) and snapshot-backup.zip.feTlPR (261 MB).
Can it be connected with max_execution_time of 30 seconds which cannot be increased on my server?