Download from shareapp client on my servor NAS

i need to download file of 260Gb from my client share app to my company servor NAS.
I cant cross with my local station (not possible to have this space disk) ,i tried dowload directly into my servor NAS ,but failled with network we advise me to use NEXTCLOUD for desktop.
With difficulty i see how add a synchronisation between client and my NAS (with phisical file) ,file is currently in download but remains for 3 months.
And for information i used trial version (1 hour test if i understand) ,did you have any suggestion for this context?
PS/I am not from IT department

Thank you