https://medium.com/onlyoffice/onlyoffice-vs-collabora-a-critical-comparison-18a5ba0dee62

Collabora

My analysis is that although OnlyOffice seems to have more features, it needs FAR more hosting resources than Collabora. The minimum resources for OnlyOffice are below. In comparison, Collabora can be setup on a 1GB RAM server (using about 65% of ram). I have also managed to install rocket.chat on the same server although both are using 830 – 870MB (87%) of RAM when idle. This can work for a couple of users but not any more than that. However, 2GB of RAM is fairly comfortable for a small team and much less costly than the RAM necessary for OnlyOffice. Further tests I've done have shown having both Collabora and RocketChat in Docker containers running on a 2GB server works well for a small team. Also, I've had no problem working with Microsoft Office documents (Word, Excel, PowerPoint) with both Collabora and OnlyOffice.

OnlyOffice

https://www.onlyoffice.com/download.aspx
Community Edition is a free version of collaborative system developed to manage documents, projects, customer relationship and email correspondence, all in one place. Installing Community Server also installs the Document Server.

Installing Community Edition using the provided script
https://helpcenter.onlyoffice.com/server/docker/opensource/opensource-script-installation.aspx

Installing Community Server for Docker on a local server
https://helpcenter.onlyoffice.com/server/docker/community/docker-installation.aspx

System requirements

    CPU: dual core 2 GHz or better
    RAM: 6 GB or more
    HDD: at least 2 GB of free space
    Additional Requirements: at least 2 GB of swap
    OS: amd64 Linux distribution with kernel version 3.10 or later
    Additional Requirements
        Docker: version 1.10 or later

Document Server is an online office suite comprising viewers and editors for texts, spreadsheets and presentations, fully compatible with Office Open XML formats: .docx, .xlsx, .pptx and enabling collaborative editing in real time.

https://helpcenter.onlyoffice.com/server/docker/document/docker-installation.aspx

System requirements

    CPU: dual core 2 GHz or better
    RAM: 2 GB or more
    HDD: at least 40 GB of free space
    Additional Requirements: at least 2 GB of swap
    OS: amd64 Linux distribution with kernel version 3.10 or later
    Additional Requirements
        Docker: version 1.10 or later