I am running an old macbook pro 2009, with el capitan 10.11.6...
Search the support page (link at top), pretty sure there is a document that has links to earlier versions of NA.
Hi @Olly Mills El Capitan is no longer supported by NI unfortunately. But here 's where you can find older versions of Native Access just in case:
Native Access Legacy Installers for Older Operating Systems
Legacy Installers for Native Instruments Software Products