Browser capabilities

Hi there, total newbie here. I currently do invoicing for a family member's business and they have just transitioned to MYOB. As I do this remotely, I do not have access to the desktop application. I am also a Mac user. I assumed it would be straightforward for me to access their account via browser as MYOB states "manage your business on any device". 

I was provided with some instructions from the business but the information relates to the desktop version which seems very different to the browser.
Eg. Select Sales tab
Enter Sales 
New Sale
Record
Sales Register

On the browser version, I've clicked on
> Create
> Sales
> Invoice 
which I assumed is what I need to get into to start an invoice/sale. When I open that I get the message   "This invoice is read only because the layout isn't supported in the browser. Switch to AccountRight desktop to edit this invoice.". 

Is it correct that I cannot use this function/create invoices while on the browser? If so, that's very odd for something that claims to "manage your business on any device". 

I just want to have access to create invoices for the business, nothing further. If I cannot use the browser, what is the recommendation / process for getting the desktop version on my computer.

Thank you kindly.