Updating to 4.1.0-beta won't update and I get the following ...

Unable to open archive
Update path does not exist

Error updating COM_INSTALLER_TYPE_TYPE_.

Am testing the free version before buying and am perturbed that this basic functionality isn't functional by error or design.

Any assistance is grateful

Installed V 4.0.0-beta1 Standard

When I click on Control Panel link I get a blank page

Link: domain.com.au/administrator/index.php?option=com_joomdoc

Error reporting shows
Parse error: syntax error, unexpected T_PAAMAYIM_NEKUDOTAYIM in domainname/administrator/components/com_joomdoc/libraries/joomdoc/utilities/helper.php on line 68

Any thoughts as to why?
What to do to repair that situation?

Thanks

----- edit -------
Discovered that the update to 4.0.1-beta is dysfunctional

Unable to open archive
Update path does not exist