in macOS

when i right click a file (pdf, document, etc.) and the click "Open with" and select OnlyOffice, the file opens properly. however if i do those same steps and select the option to "Always open with", when I go to open another file by just double clicking, I get an error saying it was not opened and "Apple could note verify [file name] is free of malware that may harm your Mac or compromise your privacy." along with two button options: Move to Trash and Done. this happens with any file. i've been trying to search for a solution to this issue but can't seem to find; do others have this issue and if so, please help if you've figured it out! thank you :)