Im trying to upload a 45MB file but its failing, is there any way to change it? And also what are all the file extensions not allowed to upload in SharePoint document library?
What is the file size upload limit for SharePoint online?
the File upload limit for SharePoint Online in Office 365 Business Essentials and Office 365 Business Premium is 10 GB per file and file attachment is 250Mb.
Note: In classic mode, upload methods other than drag and drop have a 2 GB limit.
For more details check Limits for SharePoint Online in Office 365 Business Essentials and Office 365 Business Premium
Is there any way to change file size to allow me to upload a file?
You can't change these settings in SharePoint online.You can change the file size upload limit in an on-premises environment, but it's not possible in SharePoint Online because it's a shared setting for all the tenants.
No restrictions to types of files added to SharePoint Online, reference, https://support.office.com/en-us/article/types-of-files-that-cannot-be-added-to-a-list-or-library-30be234d-e551-4c2a-8de8-f8546ffbf5b3