but please note that if there just compatiblity issue with few plugins then no issue, i'll help but if they are too many then i will not help you for free.
before reply please check file permmission and tell me when you reply
777 recursive permission (all folders and files within a folder)
ow_pluginfiles/
ow_static/
ow_userfiles/
777 non recursive permission:
ow_smarty/template_c
please share the FTP logins, and website moderator logins via private message if yo want me to install and setup.