RSelenium rdDriver() Could not open chrome browser - r

Question

My code:
driver <- rsDriver(browser="chrome", port=4234L, chromever = "89.0.4389.23")
and output:
checking Selenium Server versions:
BEGIN: PREDOWNLOAD
BEGIN: DOWNLOAD
BEGIN: POSTDOWNLOAD
checking chromedriver versions:
BEGIN: PREDOWNLOAD
BEGIN: DOWNLOAD
BEGIN: POSTDOWNLOAD
checking geckodriver versions:
BEGIN: PREDOWNLOAD
BEGIN: DOWNLOAD
BEGIN: POSTDOWNLOAD
checking phantomjs versions:
BEGIN: PREDOWNLOAD
BEGIN: DOWNLOAD
BEGIN: POSTDOWNLOAD
[1] "Connecting to remote server"
Selenium message:Timed out waiting for driver server to start.
Build info: version: '4.0.0-alpha-2', revision: 'f148142cf8', time: '2019-07-01T21:30:10'
System info: host: 'blah.blah.blah', ip: '2601:602:9403:400:0:0:0:f690%en0', os.name: 'Mac OS X', os.arch: 'x86_64', os.version: '10.15.7', java.version: '15.0.2'
Driver info: driver.version: unknown
Could not open chrome browser.
Client error message:
Summary: UnknownError
Detail: An unknown server-side error occurred while processing the command.
Further Details: run errorDetails method
Check server log for further details.
I have also used chromever="latest" and tried different ports. The selenium-server-standalone.jar is in the working directory as well as the chromedriver.exe in case that is important.
I have been able to start a selenium server on this port from the command line using the same .jar and .exe files and then tried the code
browser <- remoteDriver(port = 4234L, browserName = "chrome")
browser$open()
only to get the error:
Selenium message:Unable to create new service: ChromeDriverService
Build info: version: '4.0.0-alpha-2', revision: 'f148142cf8', time: '2019-07-01T21:30:10'
System info: host: 'blah.blah.blah', ip: '2601:602:9403:400:0:0:0:f690%en0', os.name: 'Mac OS X', os.arch: 'x86_64', os.version: '10.15.7', java.version: '15.0.2'
Driver info: driver.version: unknown
Error: Summary: SessionNotCreatedException
Detail: A new session could not be created.
Further Details: run errorDetails method
I feel as if the "Driver info: driver.version: unknown" is the problem, which I think refers to the chromedriver but I'm not sure. I am quite positive that "89.0.4389.23" is my chrome version and that java, selenium, chrome are all very up-to-date versions.
Any thoughts would be appreciated, thanks.